Timer

ABSTRACT

The outer ratchet wheel is a part of the timing cam drum of a step-by-step type of interval timer. The outer ratchet is advanced by means of a pawl which is reciprocated as the slow rise fast drop cam rotates to retract the pawl one tooth and advance the pawl with a snap action until the pawl abuts a stop member, at which time the retaining pawl engages the same tooth to hold the cam in place. At certain intervals or positions on the outer ratchet the teeth are missing thereby allowing the drive pawl (and then the retaining pawl) to &#39;&#39;&#39;&#39;reach inside&#39;&#39;&#39;&#39; and engage a time delay ratchet which is then advanced inside the outer ratchet a number of steps until the inner ratchet engages the inside of the outer ratchet and starts driving the outer ratchet until the drive pawl and retaining pawl are back onto the outside ratchet, at which time the inside ratchet is released and returned to its original point by the spring bias. This allows what would normally be a short interval on the outer ratchet to be &#39;&#39;&#39;&#39;stretched&#39;&#39;&#39;&#39; to provide a long interval without consuming too many steps of the timing cam.

Waited States aterrt [1 1 @bermann [54] TIMER [75] Inventor:

[73] Assignee:

George Obermann, Niles, lll.

Controls Company of America, Mel- 51 Apr. 3, 1973 PrimaryExaminerCharles J. Myhre Assistant Examiner-Wesley S. Ratliff, Jr.Attorney-John N. Michael et al.

[57] ABSTRACT The outer ratchet wheel is :1 part of the timing cam drumof a step-by-step type of interval timer. The outer ratchet is advancedby means of a pawl which is reciprocated as the slow rise fast drop camrotates to retract the pawl one tooth and advance the pawl with a snapaction until the pawl abuts a stop member, at which time the retainingpawl engages the same tooth to hold the cam in place. At certainintervals or positions on the outer ratchet the teeth are missingthereby allowing the drive pawl (and then the retaining pawl) to reachinside and engage a time delay ratchet which is then advanced inside theouter ratchet a number of steps until the inner ratchet engages theinside of the outer ratchet and starts driving the outer ratchet untilthe drive pawl and retaining pawl are back onto the outside ratchet, atwhich time the inside ratchet is released and returned to its originalpoint by the spring bias. This allows what would normally be a shortinterval on the outer ratchet to be stretched to provide a long intervalwithout consuming too many steps of the timing cam.

3 Claims, 4 Drawing Figures TIMER CROSS-REFERENCE TO RELATED APPLICATIONThe specific drive mechanism here, i.e. without the interval stretchingfeature of this invention, is shown and claimed in U.S. Pat. No.3,395,585.

BACKGROUND OF THE INVENTION Washing machine timers are classicallyadvanced in a step-by-step manner at timed intervals. Generally theangular step of the timing cam is 7.2 (50 steps for a total revolution)or in some cases 6 (60 steps), which represents about the practicalminimum for proper operation of the timer. Thus, only 50 or 60 steps areavailable in a complete revolution of the timing cam and obviously onlyone revolution is available since the programs then begin to repeat.

There is an increasing demand for various programs for different washingprograms. Thus there is a squeeze on the designer to provide moreprograms within the 360 rotation of the timing cam. Coupled with thisdesire there is a desire to provide for long soak periods and the likewhich normally consume a considerable number of steps in the timingadvance sequence. Therefore, it is desirable to provide some way ofproviding long intervals while still being able to provide a number ofprograms on the timing cam.

SUMMARY OF THE INVENTION This invention is directed to provision ofapparatus which permits stretching of selected intervals so as toconsiderably increase the effectiveness of the timer. Thus a desirablenumber of programs can still be provided on the timing cam, desirablestep increments can be retained i.e. 6 or 7.2) and still the selectedintervals can be substantially increased. The construction described inthe Abstract, in effect, allows the timing cam to be parked while thestretched interval occurs. At the conclusion of the stretched intervalthe advance mechanism once again starts driving the timing cam. Thisarrangement can be provided without greatly increasing the cost of thetimer.

DESCRIPTION OF THE DRAWING FIG. 1 is a bottom plan view of the escapemechanism taken on meandering line as shown in FIG. 2.

FIG. 2 is a fragmentary vertical section with parts broken away showingthe orientation of the stepping ratchet and time lapse ratched to thetiming cam.

FIG. 3 is a fragmentary view showing the manner in which the drivemechanism can actuate the time lapse ratchet while the stepping ratchetremains stationary.

FIG. 4 is a view comparable to FIG. 3 but shows a position of the partsafter the drive mechanism has returned to the stepping ratchet and thetime lapse ratchet is in process of returning to its starting point.

DESCRIPTION OF PREFERRED EMBODIMENT the drive pawl 14 mounted on pivot16 carried by lever 18 which is journaled on the same axis as the timingcam. The free end of the lever 18 is actuated by a slow rise fast dropcam 20 which will gradually depress the lever (as seen in FIG. 1) tomove the pawl back a tooth and when the end of the lever reaches thedrop face of the cam the lever rapidly drops to the low point on the camand drives the pawl forward to advance the stepping ratchet 12 and theassociated timing cam forward one step. Lever 18 is spring biased in acounterclockwise direction as viewed in FIG. 1. The biasing spring isnot shown since such arrangements are known in the art. The length ofthe drive step is determined by engagement of the end of drive pawl 14with the stop member 22 pivoted on pivot 24 and underlying the I holdingpawl 26. During the advance stroke, the holding pawl is cammed out ofengagement with the ratchet but as soon as the stroke is completed thelarge tooth on the end of the holding pawl drops into the adjacent spacebetween the ratchet teeth to retain the ratchet in position. Both theholding pawl 26 and the drive pawl 14 are biased into engagement withthe ratchet teeth by a single spring 28. The drive mechanism thus fardescribed is that shown in the aforesaid patent.

As may be seen in FIGS. 1 and 2, teeth are missing at the variouslocations around the periphery of the stepping ratchet. Thus teeth aremissing at 30, 32, 34, 36, 38 and 40. These gaps correspond to positionsof the timing cam at which a long interval is desired.

Interval ratchet 42 is rotatably mounted on the hub 44 of the timing camdrum harbor so that it can rotate relative to the timing cam drum. Thespring 46 coiled around the shaft portion 48 of the inside ratchetmember is connected to the ratchet member at 50 and is connected to thetiming cam arbor at 52 so that the ratchet is biased in a clockwisedirection (FIG. 1) to position the tooth 54 in abuting relation to theradially inwardly projecting face or portion of 56 of the outer ratchet.The rotatable mounting of the inner ratchet wheel relative to the outerratchet will permit the inside ratchet wheel to be moved relative to theouter ratchet wheel until the lug 58 on the inner ratchet hits face 60on the inwardly projecting portion of the outer ratchet at which timeany further effort to move the inner ratchet would force the outerratchet to move with the inner ratchet. Now then, as pointed out above,the various gaps in the outer ratchet correspond with positions in theprogram timing cam at which a long interval is desired. It should beborne in mind that the entire program timing cam may actually providefor a number of programs. In FIG. 1 the advancing pawl 14 has moved theouter ratchet to a position immediately adjacent the gap 36 at whichtime an interval would be desired. When the pawl next advances it willdrop into the hold and hit the flat tooth 62 on the inner ratchet. Theantireverse pawl 26 will also land here and will restrain the outerratchet. On the next step the ratchet will slide the advance pawl backalong the flat tooth 62 until it lands inthe adjacent notch in the innerratchet and then the advance stroke will move the inside ratchetrelative to the outside ratchet whereupon the anti-reverse pawl willengage the inner ratchet to hold it in its advanced position against thebias of the return spring 46. The auxiliary anti-reverse pawl 64 holdsthe outer ratchet. During this step it is obvious that no movement ofthe outer ratchet occurred and hence the timing cam remains stationary.Thus it is now necessary to advance the inner ratchet relative to theouter ratchet until such time as the lug 58 engages face 60 to pick upthe outer ratchet and transfer advance motion to the outer ratchet andhence the timing cam. This will, of course, force the advance pawl andthe anti-reverse pawl to rise up and start operating on the steppingratchet. Upon release of the inner ratchet, the return spring 46 returnsit to its starting point so that the full stretched interval will beavailable when next the timer is advanced to a position where alonginterval is desired. As shown, that next position would be adjacenttooth 66 and the next movement of the advance pawl would drop down intonotch 68 on the inner ratchet.

Since the nature of the advance mechanism per se is such as to permitvariable steps it is possible to vary the interval or provide differentintervals at different cutouts in the outer ratchet simply by varyingthe tooth spacing of the inner ratchet portion which will be effectivefor the stretched interval. Thus the number of steps in effect can bedecreased for a given stretched interval and therefore not all stretchedintervals need be the same. The versatility afforded by this arrangementin programming the timer greatly increases the mount of programmingwhich can be effected by a timer without unduly increasing the diameterof the drum and hence the size of the timer.

FIG. 3 shows the position of the advance mechanism while it is drivingthe inside ratchet relative to the outside ratchet. This alsoillustrates the manner in which the holding pawl operates on bothratchets during the stretched interval phase of operation. FIG. 4illustrates the position in parts after the mechanism has returned tothe outer ratchet and (with some artistic license) the inner ratchet isshown in the process of returning to its zero point.

I claim:

1. A program timer of the type advanced in a stepby-step manner tosequentially actuate switches in accordance with the rotational positionof the program cam, comprising,

a ratchet wheel having spaced teeth,

a stepping mechanism including an advance pawl engageable with theratchet wheel to advance the ratchet wheel in a step-by-step manner tosequential positions determining the position of the program timing cam,some of the teeth of the ratchet being omitted in at least one positionon the periphery of the ratchet so as to leave a gap through which theadvancing pawl may project inwardly, second ratchet wheel positionedinside the first with teeth underlying the gap in the outer ratchetwheel whereby the advancing pawl will operate through the said gap ontothe inner ratchet wheel and advance it in a step-bystep manner,

said inner ratchet wheel being biased to an initial position and beingrotatably relative to the outer ratchet wheel to a second position inwhich the inner and outer ratchet wheels become engaged and move inunison whereby the timing cam remains stationary during such period asthe advancing pawl is advancing the inner ratchet relative to the outerratchet and upon the two ratchets becoming interengaged the advance pawlreturns to the outer ratchet and is disengaged from thejnner ratchetwhich then returns 0 its initial position under influence of its sprm gbias.

2. A timer according to claim 1 including holding means operative toengage said outer ratchet during each back step movement of theadvancing pawl and thereby prevent movement of the program timing cam inthe interval between the advancing steps,

second holding means operative on said inner ratchet wheel to retain itin its advanced position relative to the outer ratchet 'wheel during theinterval between advancing steps imparted to the inner ratchet wheel.

3. Apparatus according to claim 2 in which the holding means for bothratchet wheels are carried by the same member and comprises holdingpawls,

one of said holding pawls engaging the outer ratchet until it reachessaid gap and thereupon engaging the inner ratchet,

the other holding pawl being an auxiliary pawl which engages the outerratchet while the first holding pawl engages the inner ratchet.

1. A program timer of the type advanced in a step-by-step manner tosequentially actuate switches in accordance with the rotational positionof the program cam, comprising, a ratchet wheel having spaced teeth, astepping mechanism including an advance pawl engageable with the ratchetwheel to advance the ratchet wheel in a step-bystep manner to sequentialpositions determining the position of the program timing cam, some ofthe teeth of the ratchet being omitted in at least one position on theperiphery of the ratchet so as to leave a gap through which theadvancing pawl may project inwardly, a second ratchet wheel positionedinside the first with teeth underlying the gap in the outer ratchetwheel whereby the advancing pawl will operate through the said gap ontothe inner ratchet wheel and advance it in a step-by-step manner, saidinner ratchet wheel being biased to an initial position and beingrotatably relative to the outer ratchet wheel to a second position inwhich the inner and outer ratchet wheels become engaged and move inunison whereby the timing cam remains stationary during such period asthe advancing pawl is advancing the inner ratchet relative to the outerratchet and upon the two ratchets becoming interengaged the advance pawlreturns to the outer ratchet and is disengaged from the inner ratchetwhich then returns to its initial position under influence of its springbias.
 2. A timer according to claim 1 including holding means operativeto engage said outer ratchet during each back step movement of theadvancing pawl and thereby prevent movement of the program timing cam inthe interval between the advancing steps, second holding means operativeon said inner ratchet wheel to retain it in its advanced positionrelative to the outer ratchet wheel during the interval betweenadvancing steps imparted to the inner ratchet wheel.
 3. Apparatusaccording to claim 2 in which the holding means for both ratchet wheelsare carried by the same member and comprises holding pawls, one of saidholding pawls engaging the outer ratchet until it reaches said gap andthereupon engaging the inner ratchet, the other holding pawl being anauxiliary pawl which engages the outer ratchet while the first holdingpawl engages the inner ratchet.